sea to summit Air Stream Pump Dry Sack. The Air Stream is Sea to Summit's big volume sleeping mattress pump, it's based on their 20L Ultra Sil Nano Dry Sack, with added valve plug and foot loop. The 20 liter Air Stream can be inflated with a single breath. Two to three cycles from the Air Stream are enough to fill Sea to Summit sleeping mats, so you're ready to go quickly, with minimal breath condensation in your mat or dizziness from blowing the mat up. The Air Stream can be used as a 20L dry sack or ultralight pack liner.